In an "Ask Us Anything" posted today, ZeniMax Online developers answered several "Elder Scrolls Online" PvP oriented questions. Other questions were also answered, but there are a few PvPers need to see.
Highlights from the 10 questions answered include the size of groups for PvP, a PvP ranking system, the rate of leveling in PvP, and much more. First off, groups larger than the standard group size will be supported in PvP. Details, like the size of the larger group, are yet to be announced, however.
A PvP ranking system will be present. As Alliance Ranks are earned, players can buy new weapons and armor. Even new PvP abilities are unlockable. Finally, players will be able to level from 10-50 in Cyrodiil by PvPing. It may not be as fast as leveling in the PvE world considering the availability of fights, but there are other "activities" in Cyrodiil to supplement the leveling process.
For full answers to these questions, and a few more, check out the official site.